# `foo` is an integer and this statement will return two rows.
sth = dbh.prepare("select foo from bar")
# would raise InterfaceError if called here
sth.execute
sth.bind_coltype(1, DBI::Type::Varchar)
# would normally use DBI::Type::Integer and return a Fixnum. We'll make it a string.
sth.fetch => ["1"]
# Here we coerce it to Float.
sth.bind_coltype(1, DBI::Type::Float)
sth.fetch => [1.0]
sth.finish